Valve-lash-compensating device



April 3, 1928.

C. R. SHORT VALVE LAsH COMPENSATING DEVICE Filed April 16H 1.925 Z0 Il; u

Patented Apr. 3, 1928.

UNITED STATES 1,664,710 PATENT OFFICE.

CHARLES R. SHORT, OF DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS RESEARCH CORPORATION, OF DETROIT, MICHIGAN, .CORPORATION OF DELAWARE.

VALVE-LASH-conrnnsn'rrno nnvron.

Application led April 16, 1926. Serial No. 102,522.

This invention'relates to means for taking up back-lash which may result from wear or variations of heat conditions in the valve operating rods and tappets of internal combustion engines.

The invention consists inthe combination of a valve operating rod and tappet interposed between the valve and the cam shaft, said valve and tappet being automatically extensible and being connected by a one-way operating rod-clutch which locks said valve and tappet in extended position during the opening movement; said clutch being tripped and released near the end of the closing movement of the valve.

In the accompanying drawings in which like reference characters indicate like parts about the several views:

Fig. 1 is a vertical transverse section through one cylinder and head of an internal'combustion engine, exposing a valve and valve operating mechanism;

Fig. 2 is a section of a fragment ofthe valve operating mechanism; and

Fig. 3 is a section disclosing a modified form. v

In Fig. 1 there is illustrated an engine of the valve in head type, with this invention embodied. The invention, however, is not limited to use with the valve in head type but ma obviously be applied to the operation o valves in L-head or other engines.

In Fig. 1, numeral 10 indicates a cylinder,

11 a detachable'head; 12 the crank shaft, 13

the connecting rod and 14 the piston. 15

indicates a valvek port, 16 a poppet valvel adapted to open and close said port, 17 a valve stem, and 18 a spring arranged to close the valve. 19 represents a rocker arm carried by the shaft 20 which is mounted in bearing lugs 21 rising from the cylinder head 11. One end of the rocker arm bears upon the end of the valve stem 17, while the other end is connected by the ball joint 22 with a push rod 23. v y

The push rod 23 forms one element of an operating member composed of a telescoping pair of elements, the other element being represented by the valve tappet 24 which is yrepresented in this case as having a hollow interior 25 and a flattened head 26 which is adapted to be engaged by the cam 27 on valve operating shaft 28. The operating member. is` biased toward an extended position/.by gravitation or spring or both. The

valve tappet 24 slides in a bearing sleeve 29 which is fitted into a hole provided for it in the cylinder casting 10. In the form shown in Fig. 1, one side of the valve tappet 24 is longer than the other, so that the point 30 approaches nearer to the rocker arm 19 than the portion 31, for a purpose to be presently described. Sleeve 29 is threaded at its upper end. On this threaded end is a nut 32 which may be adjusted on said threaded end and be locked in position by lock nut 33. Pinned to push rod 23 is a spring seat 34 engaged by a coiled compression spring 35. A loop clutch or cramp plate 36 is adapted to engage the push rod 23, spring 35 being so disposed as to exert pressure upon said loop clutch. This type of clutch may consist of a plate having a hole in it of such size as to permit the plate to slide freely on the rod when it is substantially at right angles to the rod, but to seize the rod when it is tilted. It will be obvious from the construction previously described that the extended point 30 of the tappet engaging under the loop clutch plate 36 wlll cock or tilt said plate and cause it to seize upon the rod 23 when the tappet is advanced by 'the cam. Thus, as the tappet advances in the direction to open the valve the clutch will seize the rod 23 and carry it with the tappet.

At al1 times the spring 35 aided by grav ity in upright engines, tends to extend the operating member consisting of the tappet and push rod 23 as far as the cam 27 and the rocker arm 19 will permit. The spring and mass of the tappet thus tend to take up automatically at all times any playor lost motion that might otherwise come about by reason of wear or change of position due to expansion of parts under the influence of changes of temperature. When the operating member is extended to the possible limit, the clutch plate will be tilted in position to seize upon the rod so that when the impulse is given to the tappet to open the valve there can be no contraction of the operating member. l

The construction thus far described, provides that all wear produced by the friction of moving parts which would otherwise cause lost motion is taken up by the spring and is retained, due to the coaction of the clutch, tappet and push rod. Should changes in the reverse direction take place, that is, should the operating member have elongated during conditions of extreme heat so that it would be too long under conditions of less heat, the clutch will automatically release and permit the contraction of the member. This release occurs in the construction shown in Fig. 1 by reason of the engagement of the lower side of the clutch loop plate with the nut 32 which functions as a trip. lin the construction shown, near the end of each closing movement of the valve, the clutch loop plate comes in contact with the trip, thus unlocking the connection between the tappet and rod and permitting the operatlng member to readjustl itself to the proper length.

` Fig. 1 shows the clutch vplate locked to the rod 23 while Fig. 2 shows the clutch plate tripped and the operating member free to contract as may be required.

The modification shown in Fig. 3 operates substantially like that shown in Fig. 1. Tn Fig. 3 the tappet 24a slides in a guide 29 and has an upper threaded end on which are threaded the trip nut 32L and lock nut 33a. The portion 25a within the tappet is somewhat larger than that shown in the other form in order to accommodate an enlarged end 2,3a on the lower end of the push rod 23. Tn the upper end of the tappet 24a, a number of notches 38 are adapted to function as seats for balls 39. Thus the upper end of the tappet 24a, notched as described, constitutes a ball cage. Freely slidable over the upper end of the enlargement 37 is a conical clutch member 40. This clutch member is forced toward the tappet by its spring 35 which is disposed between said clutch member and the spring seat 34. Between the tappet 24a and the inner upper end of the clutch member 40 there is a relatively light coiled spring 41 so that the expansion of the spring-35 operates through the clutch member 44 and the spring 41 to extend the valve operating member consisting of the push rod 23 and the tappet 24a, in order to take up the entire space between the operating cam 27 and the rocker arm 19.

Tn the operation of the modified form of the invention the tappet and push rod being extended to their limit, engagement of the tappet head 26 by the cam 27 will effect engagement during the valve opening stroke between the tappet and the push rod through the clutch member 40 and balls 3S), thus maintaining a positive transmission from the cam 27 to the rocker arm. Should the parts change position by reason of cooling of the engine the clutch yconnection between the tappet and the push rod will be tripped as the valve approaches closed position by engagement of the clutch member 40 with the trip 32a.

Although the improved automatic take-up device has been shown and described in connec'ticn with a valve in head engine, it is naamw also adapted to other forms of engines, the essential features of the invention lying in the automatic extensible operating member, the automatic clutch operating to make said members rigid during the valve closing stroke and releasing the clutch near the end of the valve closing stroke to permit automatic readjustment of the length of said operating member. While I have described and illustrated two specific operative embodiments of the invention it is not intended that the invention shall be limited to the specific forms described and illustrated but only by the scope lof the appended claims.

What T claim is:

1. Tn valve operating means, an automatically adjustable operating member comprising a telescoping rod and tappet interposed between the valve and a valve operating shaft, said rod and tappet having a bias toward extended position, a clutch adapted to lock said rod to said tappet during the valve opening stroke and a stationary trip for releasing the clutch during the valve closing stroke.

2. Tn a valve operating means, an operating member comprising a telescoping rod and tappet interposed between the valve and valve operating shaft, a spring tending to extend said operating member, a clutch adapted to lock said rod to said tappet during the valve opening stroke and a stationary trip for releasing the clutch'during the valve closing stroke.

3. In a valve operating means, an operating member comprising a telescoping rod and tappet interposed between the valve and valve 'operating shaft, said rod and tappet having a bias toward extended position, a guide bearin for said tappet, a clutch adapted to lock said rod to said tappet during the valve opening stroke, and means for releasing the clutch during the valve closing stroke consisting` of an adjustable trip adjacent the guide bearing in. position to engage and trip the clutch.

4. lin` a valve operating means an operating mechanism comprising a telescoping rod and tappet interposed between the valve and valve operating shaft said rod and tappet having a bias toward extended position, a clutch adapted to lock said rod to said ta pet during the valve opening stroke, a gui e bearing for said tappet and means for releasing the clutch during the valve closing stroke comprising a nut threaded on the guide bearing in position to engage and release the clutch.

5,. lin a valve operating means, an operating mechanism comprising a telescoping rod and tappet interposed between the valve and valve operating shaft, a spring tending to extend said rod and tappet, a tiltable loop clutch plate adapted to engage said rod, said plate being disposed between the spring and ias ' the taplpet and said tappet having an end adapte to tilt the plate during the valve opening stroke and a trip disposed in the path of the plate during the valve closing movement adapted to release the grip of the plate upon the rod.

6. In a Valve operating means, an operating member comprising a telescoping rod and tappet interposed between the valve and 10 valve operating shaft, a clutch supported by the tappet adapted to lock the tappet to the rod durlng the Valve opening stroke, a spring bearing upon said clutch and rod, said sprin exerting its elastic force to unlock the clutc and extend said teleseoping rod and tappet 15 during the valve closin stroke and a stationary trip to hold the c utch unlocked when the operating member is fully extended.

In testimony whereof I ailx my signature.

CHARLES R. SHORT. 

